David Scott has PC2000 running in SheepSaver under Sierra and is even able to open ClarisCAD files.

Because of changes in the OS and the programming supplied by Apple, older files are at risk.

PowerCADD has legacy translators that will open files back to PowerDraw 4, but nothing earlier. These translators are not automatically loaded when PowerCADD fires up, and you have to hold down the Option key when starting PowerCADD to load the legacy translators.

Even with these legacy translators, you are running some risk in delaying to do the updating because at some point there will be a change in the OS or Apple's programming that will not run. Nobody can tell you when that will happen.

If you have the legacy translators loaded (with Option key as described above), then you can go to a directory select all of the old PowerCADD files and drag them as a group over the PowerCADD icon on the dock. You will have to click in a dialog to confirm that you want to open the files, you poor thing, but once the file is open it has already been translated and saved. You have only to close each open file. Old files should still be selected, and you can delete them or drag them to an archive location. I really don't see the point of this because it's unlikely you will even have a better translation. It can only get worse over time.

If you want to keep a disk drive with Snow Leopard and an old copy of PowerCADD, that's fine. But I urge everyone to convert all files to .PC9 format.